A challenge in the exploration and treatment of internal areas of the human anatomy has been adequately visualizing the area of concern. Visualization can be especially troublesome in minimally invasive procedures in which small diameter, elongate instruments, such as catheters and endoscopes, are navigated through natural passageways of a patient to an area of concern either in the passageway or in an organ reachable through the passageway.
Detailed information regarding the anatomy can be discerned from direct viewing of the anatomy provided through one or more of the elongate instruments used in the procedure. Various types of endoscopes configured for use in various passageways of the body such as the esophagus, rectum or bronchus can be equipped with direct viewing capability through the use of optical fibers extending through the length of the scope, or with digital sensors, such as CCD or CMOS. However, because endoscopes also provide a working channel through which other medical instruments must pass, optional lighting bundles and components to provide steering capability at its distal end, the scope is typically of a relatively large diameter, e.g., 5 mm or greater. This large diameter limits the use of the endoscope to relatively large body channels and prohibits their use in smaller ducts and organs that branch from a large body channel, such as the biliary tree.
Typically, when examining small passageway such as the bile duct or pancreatic duct, the endoscope is used to get close to a smaller passageway or region of concern and another instrument, such as a catheter, is then extended through the working channel of the endoscope and into the smaller passageway. The catheter can be routed over a guide wire pre-placed in the area of interest. Alternatively, a catheter of the steerable type may be steered into the smaller passageway with the aid of images provided from the endoscope, or if the steerable catheter has its own vision capabilities, steered into the smaller passageway with the aid of images provided by the catheter. One such steerable catheter with vision capabilities is described in co-pending U.S. application Ser. No. 11/089,520, filed Mar. 23, 2005, which is hereby incorporated by reference. Once the catheter is in the small passage areas, visualization may be provided via contrast media and/or the vision capabilities of the catheter.
Visualization may reveal selected areas within the area of interest, such as the common bile duct, that require treatment. To treat the selected areas, a different catheter is sometimes required, necessitating a catheter exchange. A catheter exchange typically involves removing the first catheter from the endoscope over a guide wire pre-placed in the area of interest, and advancing a second catheter over the guide wire to the desired treatment site. In order to maintain a handle on the proximal end of the guide wire, it is necessary that the portion of the guide wire that remains outside the patient be longer than the length of the catheter. Therefore, a catheter/guide wire system suitable for these procedures has required the use of long guide wires that can be cumbersome to manipulate and can clutter an operating room.
To address the issues associated with changing catheters over long guide wires, many non-steerable catheters include so-called “rapid exchange” lumens or channels. These rapid exchange catheters typically include an opening on the sheath of a catheter and a slot that extends along the length of the catheter through which a guide wire can be pulled. To exchange the catheter for another device while maintaining the position of the guide wire in the body, the catheter is stripped off the guide wire by pulling it through the slot. A new catheter or device can then be routed over the guide wire by inserting the proximal end of the guide wire into an opening of a guide wire lumen at the distal end of the new device and advanced such that the proximal end of the guide wire exits the opening. The opening may be positioned towards the proximal end of the catheter or may be located more towards the distal end.
While rapid exchange guide wire lumens have been developed for many procedures, they have not been adapted for use with steerable catheters, catheters with vision capabilities, catheters to be routed through the working channels of endoscopes, or catheters that are required to transmit torque from the proximal to the distal end of the catheter.
In addition to performing a catheter exchange procedure, it may also be desirable to perform a guide wire exchange procedure. This may be desirable when, for example, a first guide wire is too large to fit through a desired body duct, or otherwise lacks the desired characteristics. Under these circumstances, a physician may leave the catheter in place, withdraw the first guide wire from the catheter, and insert a second guide wire through the catheter to the desired site. During this procedure, the catheter guides the guide wire to the desired site. Thus, once the catheter is positioned at a target site, it is highly desirable to maintain the position of the catheter during a guide wire exchange procedure so that the second guide wire may be guided directly to the desired site in a minimum amount of time.